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Desperately seeking squash bees

UPDATE! In the print version of this article, this reporter inadvertently described Anthidium maculosum as a territorial leafcutter bee. It is in fact a wool carder bee. My humble apologies to the bees and the experts who helped identify them.

GREEN This summer, I hunted squash bees. The hunt began on a sunny mid-July afternoon at the home of Celeste Ets-Hokin, an advocate for native bees who lives in Oakland and has just published a 2011 calendar on the importance of conserving bee habitats.

As Ets-Hokin explains in the forward of her calendar (available from the Xerces Society for Invertebrate Conservation), "Most of our fruit, vegetable, and seed crops depend on bees for pollination. For bees, success depends on habitat, habitat, habitat."

Ets-Hokin has planted her own backyard, on a sunny ridge near Lake Merritt, with lavender, basil, and other bee-attracting plants. Although her yard was abuzz in midsummer with the sound of honey, bumble, carpenter, leafcutter, longhorn, and green metallic sweat bees, there was no sign of squash bees.

That's because squash bees only visit the blossoms of squash plants and other members of the gourd family, which Ets-Hokin doesn't grow in her yard.

So we decided to head for the trials garden next to Lake Merritt, which is funded by the University of California and the Alameda County master gardeners program.

Ets-Hokin spent the last 18 months creating a bee-attracting zone in this garden. And now she hoped to find squash bees in the garden's vegetable patch, where squash and other vegetables are tested for suitability to the local environment.

Clad in just shorts and T-shirt, Ets-Hokin looked rather vulnerable, considering she was about to go bee hunting. But, as she explained, there was no imminent threat of stings: female bees only sting those who threaten their nest, and male bees have no stingers.

"Male squash bees live to drink (nectar) and have sex with female squash bees," Ets-Hokin joked, as Rollin Coville, a lanky entomologist who has photographed insects for three decades, joined the squash bee hunt.

Dressed in a hat, slacks, and vest and hauling a state-of-the art camera, Coville was hoping to get shots of the elusive male squash bees, which emerge in late summer and can sometimes be found taking naps in the squash blossoms in the afternoon.

Last year Ets-Hokin produced a 2010 native bee calendar highlighting Coville's kickass images and informative sidebars on how to attract these native pollinators to urban yards.

This year she focused on the importance of bee habitat on farms in face of proposed food safety regulations that could undermine existing federal bee conservation programs. And she hoped to use Coville's squash bee photographs as her August 2011 pin-up shot.

But before we could escape Ets-Hokin's yard, Coville quickly withdrew a clear vial from his vest pocket, popped it over a bee on a nearby flower, then corked the vial.

The bee began to buzz furiously.

"I think it's a Anthidium maculosum," Coville declared as he uncorked the vial and let what turned out to be a territorial wool carder bee go back to its business of guarding nectar in a nearby plant.

We eventually reached the trial gardens, where Coville showed me how to pry open the fleshy yellow squash flowers that lie half-hidden below the plant's massive prickly leaves atop budding zucchini that threaten to grow as big as canoes if left unpicked.

The first dozen squash blossoms were vacant, save for a few ants and beetles, and Coville wondered aloud if late rains and a cold snap had decimated bee populations.

But then I found a squash bee sitting inside a flower like a king on a bright yellow throne. And at the next flower, six squash bees were gently napping inside.